A conventionally provided X arm type window regulator is configured as follows: a lift arm and an equalizer arm are pivotally connected to each other in an X-shaped manner; and window glass which is supported by the lift arm via a lift arm bracket is opened and closed through pivotal movement of the lift arm.
Japanese Patent Application Laid-Open No. 2003-321970 (Patent Document 1) discloses an X arm type window regulator in which a plug plate located at a central portion of an equalizer arm is fitted into a through hole located at a central portion of a lift arm, thereby pivotally connecting the arms to each other. The plug plate is a flat circular columnar plate for joining, at the central portion of the equalizer arm, a first arm and a second arm which partially constitute the equalizer arm. An end portion of the first arm is welded to one end surface of the plug plate, and an end portion of the second arm is welded to the other end surface of the plug plate, whereby the first arm and the second arm are joined together.
In the window regulator of Japanese Patent Application Laid-Open No. 2003-321970, in order to establish smooth relative pivotal movement between the lift arm and the equalizer arm at a pivotal connection of the arms without generation of play and unusual noise, one of the arms has a protrusion provided on its surface which faces the other arm, in such a manner as to protrude toward the other arm. By virtue of this, an appropriate clearance is ensured between the lift arm and the equalizer arm without influence of dimensional variations of component parts which arise in the course of manufacture.